The application of gas detector tubes to monitor the enclosed environment of a spacecraft was first done in the Skylab 2 mission. There were two contaminants of concern - carbon monoxide and toluene diisocyanate. In the Space Station Freedom program, measurement of trace contaminants in the Node 2 and Lab A atmosphere is required prior to the first entry of the crew. Since Node 2 is isolated from the trace contaminant control system for approximately 100 days during SSF building missions, it is anticipated that the Node 2 atmosphere may contain trace contaminants released over this period and some of these may exceed the acceptable levels. It will also be necessary to use gas detector tubes to measure the oxygen level since the Major Constituent Analyzer will not be powered before ingress.This paper (1) discusses the results of an analysis to calculate the levels of trace contaminants that can be expected in the Node 2 atmosphere at 100 days, (2) presents aspects of detector tube technology that may need further development for application in micro-gravity, and (3) addresses factors governing the utilization of detector tubes to monitor selected contaminants.